Water-soluble polymethine salts



United States Patent WATER-SOLUBLE POLYMETHDJE SALTS Bernard S. Wildi, Dayton, Ohio, and William B.

Tuemmler, Catonsville, MdL, assignors to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware N0 Drawing. ()riginai application July 13, 1962, Ser. No. 209,782. Divided and this application Nov. 15, 1955, Ser. No. 547,044

19 Claims. (Cl. 260-22) This invention relates to a novel method for increasing the rate of absorption of radiant energy by water, and for converting said radiant energy to thermal energy. The invention also relates to a novel method for increasing the rate of evaporation of water from aqueous solutions by the use of radiant energy, particularly solar energy. The invention also relates to novel compounds which are particularly useful with respect to the foregoing processes.

There are numerous occasions where the absorption of radiant energy by water or aqueous solutions becomes of considerable importance. One outstanding example is the recovery of dissolved solids or fresh water from sea Water by solar evaporation. Solar evaporation can also be utilized in the same manner with respect to aqueous solutions or waste waters produced in industrial plants. Solar energy, or other forms of radiant energy of comparable wave lengths, can also be utilized for heating water or aqueous solutions. All of these and similar operations are considerably enhanced by the practice of the present invention, which involves the addition of small amounts of particular additives to water or aqueous solutions to greatly increase the efliciency of absorption of radiant energy into such solutions.

It has now been found that the eifectiveness of heating and evaporating water or aqueous solutions can be very greatly increased by dissolving in the water or aqueous solution a small amount of one or more of the materials defined and described more fully immediately below. The exact amounts of these materials to be used will vary somewhat with the particular material selected-in some cases as little as one or two parts per million being sufiicient. It is generally desirable to use at least about one part per million. A preferred range of concentrations comprises between about .3 and about 25 parts per million.

The materials used according to the present invention are water-soluble phthalocyanine dyes and Water-soluble polymethine dyes. The polymethine dyes are defined as ammonium salts containing a polymethine chain terminating at either end with a nitrogen atom. A part of the polymethine chain can be included in a ring system, either aromatic or otherwise. The n in the foregoing polymethine chain formula can be any integer, including 0, but will preferably be a relatively small number, for example, not greater than about 5.

Polymethine dyes as a general class are water-insoluble compounds. They are solubilized according to the present invention by forming salts of strong pro-ton acids containing hydrophilic groups (e.g., carboxyl groups, hydroxyl groups, sulfonic acid groups, polyalkoxy groups, etc.) in excess of the acid function which is neutralized by the polymethine cation. Examples of solubilizing acids suitable for water-soluble polymethine dye salt formation are polycarboxylic (including dicarboxylic) acids, such as adipic acid, succinic acid, rnaleic acid, polymers of acrylic and/ or methacrylic acids, hydrolyzed copolymers of ethylene, isobutylene, etc. and unsaturated cyclic anhydrides such as maleic anhydride, etc.; polysulfonic acids, and particularly aromatic sulfonic acids, such as sulfonated polystyrene, etc.; and similar strong proton acids having a multiplicity of hydrophilic acid groups per molecule. The foregoing polyacids should be combined with the polymethine bases described herein in amounts such that not more than about percent, and preferably not more than about 30 percent, of the hydrophilic groups are neutralized by the polymethine bases. After formation of the water-soluble polymethine salt, the remaining free acid groups can be neutralized with metallic hydroxides such as the alkali metal or ammonium hydroxides, which will in many instances increase the water-solubility of the polymethine salt.

Another class of suitable water-solubilizing acids comprise hydroxy, and especially polyhydroxy, mono and polycarboxylic and sulfonic acids, such as citric acid, gluconic acid, mucic acid, saccharic acid, hydroxyadipic acid, malic acid, p-hydroxybenzene-sulfonic acid, naphthol disulfonic acids, etc.; other suitable water'solubilizing acids are those having the general formula where A is an acid group, such as acarboxyl or sulfonic acid group; R is a hydrocarbyl grollp, such as an aryl group, an 'alkyl group, an alkaryl group, aralkyl group, etc.; the '(OAlkyl) is a polyalkoxy chain such as is derived from ethylene oxide, propylene oxide or the like; and x is an integer from 1 to as high as 50, inclusive, preferably from about 5 to about 20, inclusive. Examples of such compounds are the polyalkylene oxide derivatives of acids such as salicylic acid, glycolic acid, naphtholsulfonic acid, p-hydroxyphenylpropionic acid, etc.

The polymethines of the present invention can be classified in three categories: (a) compounds in which each of the nitrogen atoms at the termini of the polymethine chain is a part of a heterocyclic ring system; these compounds are generally called cyanines; (b) compounds in which only one of the nitrogen atoms at the termini of the polymethine chain is in a heterocyclic ring system; these compounds are generally called hemicyanines; (c) compounds in which neither of the nitrogen atoms at the termini of the polymethine chain is in a heterocyclic ring system; these compounds are referred to hereinafter as non-cyanine polymethines. This latter type of poly: methine constitutes a novel and particularly preferred class of compounds for use according to the present invention.

These preferred non-cyanine polymethine compounds can be represented by the following general formula:

example of a salt of this class is the citrate salt of the polymethine base obtained by the alkylation of the dianilide of Nlaasg glutaconic aldehyde, which gives the following compound:

C 3 CH3 wherein n and X- are as described above.

The identity of other substituents in the molecule-Le, substitutions upon the essential structure shown above is of relatively little importance. Preferred substituents for attachment to the (terminal nitrogen atoms are alkyl hydrocarbyl groups, especially lower alkyl groups such as methyl, ethyl, isopropyl, n-propyl, n-butyl, 2-ethylhexyl, etc., but other substituents such as hydrogen atoms or other higher alkyl groups such as cetyl or stearyl groups, other hydrocarbyl groups such as alkenyl, aryl, aralkyl or alicyclic radicals, or hydrocarbyl radicals substituted with groups such as hydroxy, alk'oxy, sulfonic acid, halo (especially chloro), amino, and nitro groups, etc. are also suitable.

Preferred substituents for attachment to the terminal methine carbon atoms are aryl groups, especially aryl groups substituted with halo (particularly chloro) amino, hydroxy, alkoxy, N-alkyl and N,N-dialkylamino groups, etc., but other substituents such as those mentioned with respect to the nitrogen atom substituents of the foregoing paragraph are also suit-able.

Preferred substituents for attachment to the nonterminal methine carbon atoms are hydrogen atoms or lower alkyl groups such as mentioned above, but other substituenlts, e.g., those listed in the preceding two paragraphs are acceptableand under some circumstances even desirable.

Examples of typical compounds of the non-cyanine polymethine class are 1,3-bis(4-aminophenyl)vinylcarbonium dihydrogen citrate; 1,5-bis(4-aminophenyl)divinylcarbonium gluconate; l,7-bis(4-aminophenyl)trivinylcarbronium acid mucate; 1,5-bis[4-(N,N-dimethylamino)- phenyl]-3,4-dimethyldivinyloarbonitnn hydrogen saccharate; 1- [4- N,N-diethylamino phenyl] -7- [4- (N,N-dimethylamino)phenyl] 1 phenyl 3 ethyl 7 (4 chlorophenyl)trivi nylcarbonium hydrogen adipate; 1,1,5,5-tetrakis[4 (N,N dimethylamino)phenyl] 3 (4 chlorophenyl)divinylcarbonium hydrogen hydroxyadipate; l,7 bis{4 [N,N di(2 hydroxyethyl)aminoJphenyl} 1,7- bis(2 chl oroethyl) 4 (4 nitrophenyl)trivinylcarbonium hydrogen succinate; the 1,l,7,7-tetrakis[4-(N,N- diethylamino)phenyl]trivinylcarbonium salt of a sulfonated polystyrene having a molecular weight of approximately 10,000, in which approximately half of the sulfonic acid groups are neutralized by the carbonium base and the remainder are neutralized by sodium hydroxide; 1,5 bis [4 (N methylamino)phenyl] 1 (4 chlorophenyl)divinylcarbonium hydrogen maleate; etc.

A typical method by which the immediately foregoing and similar polymethine compounds can be prepared involves the reaction of equimolar quantities of a p-aminophenyl alkene of the class and a p-aminophenyl aldehyde (or ketone) of the class wherein n is equal to an integer'including 0, and wherein R may be either a hydrogen atom or an organic radical. These materials are allowed to react in a non-aqueous 4 solvent such as acetic acid or acetic anhydride, and the acid (the salt of which it is desired to form) is added to COOH the reaction mixture. pound of the type is formed as an intermediate which then reacts with the acid to form the desired polymethine salt.

In some cases it may be more convenient to first form the above salt of a strong inorganic acid, e.g., perchloric acid, and then convert the inorganic salt to the watersoluble salt of the present invention. This can be done by suspending the inorganic acid salt with an equivalent of a strong inorganic base, such as sodium hydroxide, in a benzene-water mixture to convert the salt to the colorless dye base. The benzene layer (containing the colorless dye base) is washed with water and then dried, e.g., over sodium sulfate. The resulting benzene solution is then mixed with an excess of aqueous solution of one of the solubilizing acids described above, and the benzene is boiled ofi leaving an aqueous solution of the watersoluble dye of the present invention.

An alternative method of preparation which can be used in making symmetrical non-cyanine polymethines having 5 or more methine carbon atoms in the polymethine chain involves the reaction of two molar proportions of a p-aminophenylalkene of the class with one mole of an orttho ester (or vinylogue of the class It is believed that an allene comthereof) OR wherein n is an integer, including 0. The procedure to be followed in this method is very much like the abovedescribed method in that the reactants are allowed to react in a non-aqueous solvent with the addition of a strong inorganic acid to form the carbonium salt, which is then converted to the water-soluble salt by the same general procedure outlined above.

The cyanine dye salts suitable for use according to the present invention can be readily prepared by formation of the strong inorganic acid salts according to well-known prior art methods, followed by conversion to the watersolubilizing acid salts by the same general procedures outlined above with respect to the non-cyanine polymethine dye salts.

The Water-soluble cyanine salts of this invention include not only the classical cyanines, in which both of the terminal nitrogen atoms are in heterocyclic rings, but also the so-called hernicyanines, in which one of the nitrogen atoms is in a heterocyclic ring and one is not. While the term cyanine was orginally applied only to compounds in which the nitrogen-containing rings were quinoline rings, the term cyanine is now used in a broader sense to include other heterocyclic nitrogen-containing r ng systems such as pyridines, indoles, benzothiazoles, benzoseleneazoles, thiazolenes, 'benzoxazoles, oeand fi-naphthothiazoles, and the likeand the term as used with respect to the present invention is intended to include these latter nitrogen-containing heterocyclic ring systems.

Examples of suitable water-soluble cyanine dye salts for use in the present invention are the succinic' acid salt of Quinoline Blue, the saccharic acid salt of Sensitol Green, the citric acid salt of dicyanine, the gluconic acid salt of kiyptocyanine, the hydroxyadipic acid salt of xenccyanine, the polyacrylicacid salt of 3,3-dimethyla 3 thiacarbocyanine, the maleic acid salt ort Ban 2000, the sulhonated polystyrene salt of Astra Violet PF Extra, the maleic acid salt of Astrazon Yellow 36, etc.

The water-soluble phthalocyanine dyes used according to this invention are phthalocyatn-ines which have been modified by forming sulfonic acid derivatives or salts thereof, sulfonamide derivatives, carboxylic acid derivatives or salt thereof, quaternary ammonium and ternary sulfonium salts, and the like. Examples of such watersoluble phthalocyanines are Heliogen Blue SBL, Durazol Fast Blue 8G8, Zapon Fast Blue HL, Sirium Light Green FFGL, copper octapyridinylacetyltetraaminophthalocyanine octachloride, etc.

The immediately following examples (Examples 1 through 13) are illustrative of the synthesis of inorganic acid salts of non-cyanine polymethine dyes from which the novel water-soluble polymethine dyes of the present invention can be prepared.

EXAMPLE 1 1,133 Tetrakis[4 (N,N Dimethylamino)Phenyl]- Vinylcarbonium Perchlorate A mixture of 1.33 grams of 1,1-.bis[-(N,N-dimethylamino)phenyl]ethylene and 1.33 grams of 4,4'l-bis(N,N- dimethylamino)benzophenone was treated with 10 ml. of phosphorous oxychloride. Reaction began immediately, with the evolution of heat and the development of a dark green-blue color. The mixture was placed on a steam bath for hours, during which time the mixture turned red. Fifteen ml. of acetic acid was then \added to the cooled mixture, which was then poured into 250 ml. of distilled water. The resulting dark red solution was treated with 3.0 grams of potassium perchlorate, followed by the gradual addition of solid sodium acetate until the mixture assumed a blue-green color and a precipitate began to form. The mixture was allowed to stand at room temperature for about an hour, during which time a dark purple solid formed. This solid was collected, washed with water and dissolved in warm methanol to give a deep blue solution which was then treated with 200 ml. of ether. Upon cooling the ether mixture, a precipitate was collected. Further washing with ether gave a 46 percent yield (based upon the benzophenone) of reddish-brown 1,1,3,3-itetrakis[4-(N,N-dimethylamino) -phenyl]viny1carboniurn perchlorate, melting with decomposition at about 238 C.

EXAMPLE 2 1,1,5,5 Tetrakis[4 (N,N Dimethylamino)Phenyl]- Divinylcarbonium Perchlorate Twenty-two and lonestenth grams of 1,1-bis[4-N,N- dimethylamino)phenyl]ethylene and 8.3 ml. of ethyl orthoformate were mixed in 50 m1. of acetic anhydride to form a slurry. To [this slurry there was added 5.57 grams of 72 percent aqueous perchloric acid dissolved in 50- ml. of acetic anhydride. The resulting mixture was heated, with gentle agitation, until the mixture became homogeneous. The mixture was allowed to stand for about 2 /2 hours, after which time an additional 8.3 ml. of ethyl orthoformate was added. After an additional 45 hours the percipitated solid wa collected and washed consecutively with acetic acid and ether. There was obtained a 96 percent yield of golden-brown 1,1,5,5-tetrakis[4- (N,N-dimethylamino)phenyl]divinylcarbonium perchlorate, melting with decomposition at 2282 29.5 C.

EXAMPLE 3 1,1,7] Tetrakis[4 (N,N Dimezhylamino)Plzenyl]- Trivinylcarbonium Perchlorate To a mixture of 1.33 grams of 1,1-bis[4-(N,N-dimethylamino)phenyl]ethylene and 0.5 ml. of 1,3,3-trimethoxypropene was added 5 ml. of acetic acid followed by 0.311 gram of 72 percent aqueous perchlonic acid dissolved in 5 ml. of acetic ianhydr-ide. Reaction started immediately, with the evolution of heat and development of an intense blue-black color. The mixture was allowed to stand at room tempenature for about 2 /2 hours, after which time another 0.5 ml. of tnimethoxypropene was added. After an additional one and one-half hours 30 ml. of anhydrous ether was added and the mixture was cooled to form a solid precipitate. The precipitate was washed with a total of 50 ml. of a 1:4 mixture of acetic anhydride and ethyl ether, washed further with pure ether, and then dried in a vacuum Ito give a 96 percent yield (based on perchlonic acid) of finely divided, brown, 1,1,7,7 tetrakis[4 (N,N dimethylamino)phenyl]trivinyl-carbonium perchlorate, melting with decomposition at 224226 C.

EXAMPLE 4 l,3-Bis[4-(N,NDimeth{ylamin0)lPhenyl] -1,3-B is(Phenyl) Vinylcarbonium Perchlorate A mixture of 2.23 grams of 1-phenyl--1-[4-(N,N-dimethylamino)phenyl] ethylene, 2.25 grams of 4-(N,N- dimethylamino)benzophenone and 20 ml. of phosphorus oxychloride was heated, with agitation, for 5 hours at about 100 C. The resulting deep red mixture was cooled, treated with 28 ml. of acetic acid, poured into 500 m1. of distilled Water, and treated with 6 grams of sodium perchlorate, followed by gradual addition of solid sodium acetate until a precipitate formed. The precipitate was separated irom the mixture, redissolved in warm ethanol and slowly cooled to give a precipitate of bronze crystals. These crystals were washed first with ice-cold ethanol, then with ether, and then dried to give a golden brown solid, melting at ISO- C. Further purification by boiling in 100 m1. of absolute alcohol, cooling the mixture to room temperature, collecting the resulting copper y precipitate, repeatedly washing the precipitate with ethanol and ether, and drying in a vacuum gave 1,3-bis[4-(N, N dimethylamino) phenyl] -1,3-bis(phenyl)vinylcarbonium perchlorate, melting with decomposition at 204-20'7 C.

EXAMPLE 5 1,5-Bis[-4-(N,N-Dirhethylamino)Phenyl]-1,5-B'i.si(Phenyl) Divirzylcarboniwm Perchlorate A mixture of 11.2 grams of 1- [4-(N,N-dimethylamino) phenyl]-1-phenylethylene, 5.0 ml. of ethyl orthoformate and 25 ml. of acetic anhydride was treated with a solution of 3.30 grams of 72 percent aqueous perchloric acid in 25 m1. of acetic anhydride. This mixture was heated in a water bath at about 8595 C. for one hour, after which another 5.0 ml. of ethyl orthoformate was added. The mixture was then allowed to stand at room temperature IfOI three hours, after which it was treated with acetic acid and ether to form a precipitate which was collected and washed with acetic acid followed by other to give a crude rust-colored product. The product was further purified by dissolving in 250* m1. of boiling acetic acid, filtering, reheating and allowing to cool slowly. A precipitate was. formed upon cooling, which, after washing consecutively with acetic acid, ethanol and ether, gave large golden-brown crystals of l,5-bis[4-(N,N-dimethyl amino) phenyl] -l ,S-bis (phenyl)divinylcarbonium perchlo r-ate, melting with decomposition at 210-21? C.

EXAMPLE 6 l,.7-Bis[4- (N,N-Dimefhylamino)Phenyl] -1,7-B is(Phenyl) vinylcarborziwm Perchlorate A mixture of 2.23 grams of 1-[4-(N,N-dimethylamino) phenyl]-1-phenylethylene, 1.0 ml. of l,3,3-trimethoxypropene and 5 ml. of acetic anhydride was treated with a solution of 0.65 gram of 72 percent aqueous perchloric acid dissolved in 10 ml. of acetic anhydride. The mixture was agitated at room temperature for about 3 minutes, and then chilled in ice for 15 minutes. A precipitate for-med, which was separated from the mixture, washed consecutively with ethanol and ether and then 7 dried. The resulting product, 1,7-bis[4-(N,N-dimethylamino)pl1enyl] 1,7 -bis(phenyl)trivinylcarbonium perchlorate, melting with decomposition at 180l81 C., was obtained in about 56 percent yield, based upon perchloric acid.

EXAMPLE 7 I,1,3-Tris[4-(N,N-Dimeihylamino) Phenyl] -3- (Phenyl) Vinylcarbonium Perchlorate A mixture of 1.33 grams of l,1bis[4(N,N-dimethylamino)phenyl]ethylene, 1.13 grams of 4-(N,N-dimethylamino)benzophenone and 10 ml. of phosphorus oxychloride was heated for 5 hours at about 100 C. The resulting dark red mixture was cooled, treated with 15 ml. of acetic acid, and poured into 250 ml. of water containing about 3 grams of sodium perchlorate. Solid sodium acetate was gradually added to the resulting dark reddishbrown mixture until a precipitate had formed and the solution had a blue-green appearance. The precipitate was separated from the solution, washed thoroughly with distilled water and dried. Further purification of the crude product by dissolution in 50 ml. of pyridine, precipitation by addition of 100 ml. of ether, and finally recrystallization from 175 ml. of absolute alcohol yielded golden brown 1, 1,3-tris [4- N,N-dimethylamino phenyl] 3-(phenyl)vinylcarbonium perchlorate, melting with decomposition at 2102l2 C.

EXAMPLE 8 J,],3-Tris[4- (N,N-Dimethylamin)Phehyl] Vinylcarbonium Perchlorate A mixture of 1.33 grams of l,1-'bis[4-(N,N-dimethylamino)phenyl]ethylene and 1.2 grams of 4-(N,N-dimethylamino)benzaldehyde was treated with 10 ml. of acetic acid, followed by a mixture of 0.65 gram of 72 percent aqueous perchloric acid dissolved in 10 ml. of acetic anhydride. The resulting blue solution was allowed to stand at room temperature for about days. Ether was added and the mixture was allowed to stand another day during which time a solid precipitated from the solution. The precipitate was collected, washed with ether and recrystallized by dissolving in 50 ml. of warm acetic anhydride, followed by cooling and dilution with about 50 ml. of ether. The mixture was chilled, and the resulting precipitate was collected and repeatedly washed with ether. Further purification by recrystallization from 25 ml. of acetic acid, boiling in 100 ml. of ethanol, cooling, and recrystallizing from 150 ml. of absolute alcohol yielded finely divided, green 1,1,3-tris[4-(N,N-dimethyle mino) phenyl]vinylcarboniurn perchlorate, melting with decomposition at 195.5197.0 C.

EXAMPLE 9 1,5-Bis{4- (N,N-Dimethylamin0) Phenyl]-1,5-Bis(4- Chloroph enyl Di vin ylcarboni um Perchlorate A mixture of 1.29 grams of 1-[4-(N,N-dimethyl=amino) phenyl]-1-(4-chlorophenyl)ethylene, 1.0 ml. of ethyl orthofor-mate and 5.0 of acetic :anhydride was treated with a solution of acetic anhydride. The mixture was allowed to stand at room temperature for about 10 minutes. It was then heated on a steam bath for 7 minutes, cooled, and chilled in ice. A dark precipitate was collected and washed with ether and recrystallized from 80 of acetic acid. Further purification by washing consecutively with acetic acid and ether, followed by drying, yielded redabuown, coppery crystals of l,5-bi-s[4-(N,N- dinrethylamino)phenyl]-1,5-bis(4 chlorophenyl) divinylcarbonium perchlorate, melting at 217-2l9 C.

EXAMPLE 10* 1 ,7-Bis[4- (N,N-Dz'methylamin0)Phenyl1-1 ,7-Bis (2,4-Dichl0rophenyl) Trivinylcarboniam Perchlorate A mixture of 5.84 grams of l-[4-(-N,N-dimethylamino) phenyl]-1-(2,4-dichlouophenyl)ethylene, 2.0 ml. of 1,3,3- tiimethoxypropene and 10 ml. of acetic anhydride was treated with 1.36 grams of 72 percent aqueous perchloric acid dissolved in 10 ml. of acetic .anhydride. Reaction began immediately, as evidenced by evolution of heat and formation of a bronze precipitate. After less than a minute, the mixture was cooled, treated with ether and the precipitate was collected. The precipitate was washed consecutively ethanol and ether to give brown 1,7- bis[4 (N,N-dimethylamino)phenyl]-1,7-bis(2,4 dichloroplienyUtrivinylcarboniu-In perchlorate, melting at 203- 204 (3.

EXAMPLE 11 l ,7-Bis[4- N ,N -Dimethylamirzo Phenyl1-1 ,7-Bis 4 -Ch loroph enyl T ri vinylcarhonium Perchlorate A mixture of 5.2 grams of 1-[4(N,N-dirnethylatrnino) plienyl]-1-(4-chlorophenyl)ethylene, 2.0 ml. of freshly distilled l,3,3-trimethoxypropene and 10 ml. of acetic anhydride was treated with a solution of 1.36 grams of 72 percent aqueous perchloric acid in 20 ml. of acetic anhy-dride. Immediate reaction was evidenced by considera'ole evolution of heat and precipitation of a solid product. After 1 minute the mixture was cooled in ice, and other was added. The precipitate was collected, washed with ethanol and then washed with ether to yield reddishbrown, crystalline 1,7 bis[4 (N,N dimethylamino) phenyl]-l,7-bis(4 chlorophenyl)trivinylcarbonium perchlorate, melting with decomposition at -496 C.

EXAMPLE l2 1 ,1 ,5,5 -Tetrakis[4- (N-Benzyl-N -M ethylamin0)Phenyl] Divinylcarbonium Perchlorate A mixture :of 5 grams of 1,1 b-is[4-(N-benzyl-N-methylamino)phenyl] ethylene, 1.5 of ethyl orthofiormate and 15 ml. of acetic anhydride was treated with a solution of 0.83 grams of 72 percent aqueous perchloric acid in 15 ml. of acetic anhydride. The resulting deep blue mixture Was warmed briefly to dissolve all of the solids, and then allowed to stand overnight, during which time a precipitate Was formed. Further agitation caused rapid crystallization of a 'coppery solid. The precipitate was collected and washed first with acetic acid and then with ether. Further purification was carried out by dissolving the precipitate in acetone, filtering the solution and then adding ethanol to the filtrate. Most of the acetone was then boiled oil, and the solution was allowed to stand several days, during which time lustrous, purple-red crystals separated. This solid was washed with ethanol and dried to give 1,1,5,5-tetrakis-[4-(I l-benzyl-N-rnethylamino)pl1enyl]divinylcarbonium perchlorate, melting at EXAMPLE 13 1 ,5-Bis[4- (N ,N-Dimethylamz'no) Phenyl]-1 ,5 -Bz's 2,4-Dz'chl0r0phenyl Di vinylcarbonium Perch lorafe A mixture of 2.9 grams of l-[4-(N,N-dirnethylamino) phenyl]-1-(2,4-dichlorophenyl)ethylene, 1.0 ml. of ethyl ortnoforrnate and 5 ml. of acetic anhydride was treated with a solution of 0.68 gram of 72 percent aqueous perchloric acid in 5 ml. of acetic :anhydride. The mixture was allowed to stand at room temperature for several minutes, then was warmed for 3 or 4 minutes and then was cooled and poured into water, whereupon a black tar-like material separated from the solution. The tarlike material was dissolved in acetone, and a reddishbrown crystalline material was precipitated by the addition of a little ether. This crystalline material was collected, washed with ether, recrystallized from acetic acid and further recrystallized from ethanol to yield golden needles of 1,5 -bis [4-(N,N-dimethyla1nino)phenyl] 1,5-bis (2,4-dichlorophenyl)divinylcarbonium perchlorate, melt ing with decomposition at about 230 C.

The strong inorganic acid salts of the polynrethine dyes prepared as described in the foregoing examples can be readily converted to the water-soluble salts of the present invention in accordance with the general pnocedure set forth in an earlier portion of this disclosure. Specific examples representative of the general pnocedure are set forth in the following Examples 14 through 19.

EXAMPLE 14 Preparation of l,1,5,5-Tetrakis[4-(N,N-Dimethylamino)- Phenyl]Divinylcarbnium Salt of Salfonated Polystyrene Symmetrical pentamethine perchlorate prepared as described in Example 2, above, was converted to the free (base 'by mixing 1.85 g. of the perchlorate salt and 0.2 g. of sodium hydroxide in 50 m1. of ethanol. Ether (150 ml.) was then added to the reaction mixture and the resulting light green solution was washed with dilute aqueous solution of sodium chloride to remove excess alkali and sodium perchlorate. The remaining green organic solution was dried over sodium sulfate, filtered and concentrated under vacuum. The concentrated dark green solution was dissolved in 150 ml. of ethanol and then vigorously stirred with 40 ml. of 0.0725 N aqueous solution of a sulfonated polystyrene (molecular weight about 10,000; average of about 1.1 sulfonic acid groups per aromatic ring; about 54% of sulfonic acid groups as free acid, the remainder as sodium sulfonate groups). The resulting solution was treated with ether to give a reddish-brown powdery precipitate which was collected, washed with ether and dried to give about a 75% yield of product salt melting above 300 C. and having infra-red absorption. Maxima at the following wave lengths (microns): 3.00, 6.25, 6.65, 7.30, 7.40, 7.80, 7.95, 8.15, 8.60, 9.05, 9.65, 10.10, 10.65, 10.90, 12.15, 13.00, 13.65, 14.90, and 15.6. The salt can be readily dissolved in boiling water to give a solution which remains stalble upon cooling to room temperature or below.

EXAMPLE 15 Preparation of 1,1,5,5-Tetrakis[4-(N,N-Dimethylamino)- PhenyIJDiVinyIcarbOnium Salt of Glaconic Acid EXAMPLE 16 Preparation of 1,1,5,5-Tetrakis[4-(N,N-Dimethylamino)- Phenyl1Divinylcarb0nium Salt of Polycarboxylic Acid (Ammoniated Capolymer of Isobatylene and Maleic Anhydride) One-tenth gram of a polycarb-oxylic acid prepared by ammoniation of the copolymer of isobutylene and maleic anhydride (1:1 mole ratio of monomers, average molecular weight about 150,000200,000) was dissolved in 100 ml. of water. Ten milliliters of the resulting aqueous solution was added to 0.5 ml. of carbonium base stock solution (see Example 15), and the mixture was boiled, thereby removing benzene and leaving an aqueous solution of the desired compound 1,l,5,5-tetral is[4-(N,N-

dinrethylamino)phenylldivinylcarbonium polycarboxylate.

EXAMPLE 17 Preparation of 1,1,5,5-Tetrakis[4-(N,N-Dimethylamin0 Phenyl]Divinylcarboniam Salt of Polyacrylic Acid A solution of polyacrylic acid was prepared by dissolving 001 gram of the acid (molecular weight about 100,000) in 100 ml. of Water. Ten milliliters of this 10 solution was added to one-half milliliter of the car bonium base stock solution (see Example 15) and the resulting solution was boiled, thereby removing the henzene and leaving an aqueous solution of the desired caribonium acrylate.

EXAMPLE 18 Preparation of 1,1 ,5,5-Tetrakis[4-(N,N-Dimethylamin0)- Phenyl1Divinylcarbonium Salt of Hydrolyzed Copolymer 07 Ethylene and Maleic Anhydride One one-hundredth gram of a polycarboxylic acid rfiormed by hydrolysis of a copolymer of ethylene and maleic anhydride (1:1 mole ratio of monomers, molecular weight about 1500) was dissolved in ml. of water. Ten milliliters of the resulting solution was mixed with one-half milliliter of the car-bionium Ibase stock solution (see Example 15) and the mixture was boiled, thereby removing the benzene and leaving an aqueous solution of the desired carbonium polycanboxylate. A trace of sodium bicarbonate was added to facilitate solution of the salt in Water.

EXAMPLE 19 Preparation of l,1,5,5-Tetrakis[4-(N,N-Dimethylam-in0)- PhenyllDivinylcarboniam Salt of Mucic Acid Three-tenths milliliter of the carbonium base stock so lution (see Example 15) was mixed with 5 ml. of a 0.05 molar solution of mucic acid in water. The resulting mixture was boiled, thereby removing benzene and leaving an aqueous solution of the desired carbonium mucate.

The following example illustrates the marked effectiveness of the various dyes of the present invention in increasing the rate of evaporation of water exposed to solar radiation.

EXAMPLE 20 Nine hundred ninety-nine and one-half gram quantities of water were placed in each of three 17.5 cm. crystallizing dishes. In one dish 10 ppm. of a phthalocyanine dye was dissolved. In a second dish 10 ppm. of the polymethine dye as prepared in Example 14 was diss lved in the water. The third dish was left with no additive in the water. The three dishes were placed on white paper out of doors in open sunlight and all-owed to stand for about 8 hours. The dishes were weighed periodically to determine the rate of evaporation of water from the dishes. The results are tabulated in the From the foregoing example it can be seen that the materials of the present invention have a very marked effect upon the rate of solar evaporation of water. It can also be seen that the novel water-soluble polymethine dye salts which constitute preferred embodiments of the present invention are over twice as efieotive in increasing this solar evaporation rate as are the less preferred (though still very effective) phthalocyanine dyes.

The subject matter embracing the disclosed process of employing the water-soluble polymethine salts in aqueous solutions to increase the rate of solar evaporation of the water is claimed in our divisional application Serial No. 209,782, filed July 13, 196-2.

We claim: I 14. The polymethine salt of claim 7, wherein R and R 1. A Water-soluble polymethine salt of the class are phenyl radicals, R" and R' are hydrogen atoms, I I I I I and X- is a polycarboxylic acid anion containing an I: N: )n= 1 excess number of free carboxylic acid groups over those 5 carboxylic acid groups neutralized by the polymethine wherein n is an integer from 0 to 5, and wherein X- is cation, a Strong proton acid anion containing liv p groups 15. The polymethine salt of claim 7, wherein R and which are present in excess of the acid function which R are chlorophenyl radicals, R" and R' are hydrogen is neutralized by the polymethine cation such that not atoms and X- is a l b li id anion containing more fl1aI1 ab'l1t 75 PBTCBIIT The hydmphili groups an excess number of free carboxylic acid groups over are neutfallzed y The Polymethme basethose carboxylic acid groups neutralized by the poly- 2. The polymethine salt of claim 1 wherein the strong proton acid anion is a polybasic acid.

3. The polymethine salt of claim 1 wherein the strong proton acid anion is a polycarboxylic acid anion having not more than about half of the carboxyl groups therein neutralized by the polymethine dye base.

methine cation.

16. The polymethine salt of claim 7, wherein R and R are (N-benzyl-N-methylamino)phenyl radicals, R" and R are phenyl radicals, and X is a polycarboxylic acid anion containing an excess number of free car- The polymethine salt of claim 1 wherein the Strong boxylic acid groups over those carboxylic acid groups proton acid anion is a hydroxy carboxylic acid anion. neutmhzed by the pcflymethme f 5. The polymethine salt of claim 1 wherein the strong j P Salt of 7, Where R is proton acid anion is the anion of gluconic acid. y )p y Iadlcal, and

6. The polymethine salt of claim 1 wherein the strong y g atoms, and is a Polycarboxylic acid proton acid anion is the univalent anion of mucic acid. anion containing an excess number of free carboxylic 7. Water-soluble polymethine salts having the strucacid groups over those carboxylic acid groups neutralized tural formula by the p-olymethine cation.

RHzC R R CHzR wherein 11 is an integer from 0 to 5; R and R are selected 18. The water-soluble polymethine Salts having the from the group consisting of hydrogen and phenyl, chlostructural formula rophenyl, dichlorophenyl, (N,N-dime-thylarnino)phenyl, I I I I I l and (N-benzyl-N-methylamino)phenyl radicals; R [/N= =CO(=G )n=G -N\]X and R are selected from the group consisting of hydrogen and the phenyl radical; and X is a wherein n is an integer from 0 to 5 and wherein X is a strong portion acid anion f om the group f strong sulfonated polystyrene polymer in which not more than proton acids containing hydrophilic groups selected from about half of the sulfonic acid groups have been neuthe group consisting of carboxyl groups, hydroxyl groups, tralized by the polymethine dye base.

sulfonic acid groups, polyalkoxy groups having the for- 19. The water-soluble polymethine salts having the mula -(Oalkyl) wherein the divalent alkyl radical 40 structural formula is selected from the group C H C H and wherein n is an integer from O to 5; R and R are selected mixtures thereof and x is a positive inte er up to 50, and from the roup consistin of hydrogen and phenyl, mixtures of the said hydrophilic groupsfand wherein the chloropheny l, dichlorophehyl, (N,N dimethylarnino) hydrophilic groups are present in excess of the acid func- I phenyl, (N-benzyl-N-methylamino)phenyl radicals, tron which is neutralized by the polymethl-ne cation such R and R are selected from the group consisting of that not more agniut t7h5 perlcent the) lhydtropliilihc hyldrogen and tlhe phenyl radial; and X is the sulfonated gr p are Bell a 1?;6 Y e P yrne 1ne ase o C arpo ystyrene po ymer in whic not more than about oneacterize the aforesaid salt with a water-solubility of at h lf of th sulfonic a id groups have been neutralized least 5 ppm. by the polymethine dye base and the balance of the sult- Thefiolylpeflfme i g P13111137, Whefem'the Strong fornc acid groups are neutralized by sodium hydroxide. pro on ac1 amon 1s a po y asic act 9. The polymethine salt of claim 7, wherein the strong References Cited m the file of thls patent proton acid anion is the anion of polycarboxylic acid hav- UNITED STATES PATENTS ing not more than about one-half of the carboxyl groups 0 2 071 9 piggott et 1 Feb 23 19 7 therein neutralized by the polymethine dye base. 2 5 37 m May 1939 10. The polymethine salt of claim 7, wherein the strong 2274732 Gaspar Mar 1942 g g-i acid anion is the anion of y y carboxylic 2,2 Breaker et 11. The polymethine salt of claim 7, wherein the 2 5 14 g'gi g i g et 1 i strong proton acid anion is the anion of gluconic acid. 2632004 Minsk et a1 1953 12. The Polymethine salt of 7, wherein the 47 1 Vinton y zsltcriang proton acid anion 1s the univalent anion of muc1c 2666761 Haselfine et a1 Ian. 19, 1954 13. The polymethine salt of claim 7, wherein R and 70 532 5 252; i g3 R are (N,N-dimethylarnino)phenyl radicals, R and R' 2719151 Haselfine et a1 n S 1955 are hydrogen atoms, and X is a polycarboxylic acid 21/353770 Brooker et a1 56 1956 anion containing an excess number of free carboxyhc acid 2,742,496 Lum et a1 APR 17 1956 groups over those carboxylic acid groups neutralized by the polymethlne cation. 5 (Qther references on following page) 13 14 Sahyun et a1 May 22, 195 6 OTHER REFERENCES Luneberg July 1956 Cook et -al.: Chemical Soc. Journ. (London), page Ingle et a1 NOV. 19, 1957 4 1944 The Chemical Action of Ultraviolet Rays, Ellis et a1., 5 Reinhold Pub Corp., New York, pages 259, 260, 261 and FOREIGN PATENTS Great Britain May 15, 1957 237 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 U99 630 Dat d July 30 1963 Inventor(s) Bernard 5. Wildi and William B Tuemmler It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

r- Column 1, lines 7-8 the portion of the Heading reading "Original application July 13 1962 Ser. No 209 782 Divided and this application" should be deleted and the following inserted therefor: Filed Column 2 line 53 the word "componnds" should read compounds Column 5, line 23 the portion of the compound name "1 l-bis (N,N-" should read l ,1 -bis [4- (N,N

Column 5 line 24 the portion of the compound name "4 ,4 l-bis (N,N-" should read 4 ,4 bis (N,N

Column 6 line 66 the portion of the compound name "vinylcarbonium" should read trivinylcarbonium Claim 7 line 10 the word "portion" should read proton Claims 7 and 19, at line 3, the portion of the formula reading I should read I R R SIGNED AND SEALED APR 7 1970 (SEAL) Attest:

Edward M. Fletcher, Ir. WmmIAM E. summon, m. Anemng Office. Comissioner of Patents 

18. THE WATER-SOLUBLE POLYMETHINE SALTS HAVING THE STRUCTURAL FORMULA 